1. Field of the Invention
The present invention relates to a method for the decolorization of colored waste water containing dyestuff and/or pigment disposed from a dyeing factory of a textile product.
2. Description of the Prior Art
For instance, in the dyeing factory of a textile product comprising a material such as cloth industrially, a large quantity of waste water containing dyestuff and/or pigment is exhausted. When such a waste water is disposed as it stands into a river, the river is polluted, and there occurs the problem of public pollution. Therefore, the waste water exhausted from the dyeing factory of a textile product has conventionally been subjected to a decolorization treatment prior to the discharge into a river. In the prior arts for the decolorization treatment of such coloring matters, there have been known the following processes: (a) by the coagulation with the addition of a suitable metal hydroxide such as of iron and aluminum, (b) by the adsorption with the use of an adsorbent such as ion exchange resin, active carbon, silica gel and alumina, (c) by the oxidation-decomposition with the use of an oxidant such as chlorine, ozone and hydrogen peroxide and (d) by the neutralization-coagulation with the addition of a polyelectrolyte having an opposite charge.
However, there are various difficulties in the above-mentioned conventional decolorization treatment methods. Namely, a large quantity of sludge is formed in the method (a), the decolorization is difficult when the waste water contains a large quantity of coloring matters in the method (b), a large quantity of decolorization chemical and a long treating time (2-3 days) are needed in the method (c) and further, in the method (d), since the waste water to be decolorized contains usually various kinds of coloring matter, complete decolorization is difficult.